pressure keeps dropping when central heating is on. Drips come out of drain off outside. Pressure goes sky high when boiler has been on for a while. Central heating has to be switched off when running shower or there is no hot water.

davidness9253@hotmail.co.uk, November 2007

hi there i have the answer to your problems ur expansion vessal is more than likely out of air and needs to be recharged thats what it sounds like gauge goes to 3 or 4 bar when on and is down to 1bar when cold is normaly expansion propblems i know this because i am an engineer peter

peter, December 2007

Exspantion Vessel pressure may be deflated causing the pressure to rise in system to over 3 bar then releasing hot central heating water out of the relief pipe(drain off) to outside.first thing to do would be to drain the heating down until the gauge on front of boiler is 0.get hold of a pressure gauge then behind the boiler at the top is a red vessel,and there is a valve(like a tire valve).make sure the gauge says its 0.8 bar,if not pump it up (with a bicycle pump)until you get that.im pretty sure its 0.8 but check your manual just to be 100%.once done fill back up then test.if thats all ok,check the relief valve if its leaking all the time,if so.......replace that.good luck

heatfactor, November 2007